Methods for protocol enhancements in 5G NAS

ABSTRACT

Methods, systems, and apparatuses for protocol data unit (PDU) session management over different access technologies (ATS) are disclosed. A wireless transmit/receive unit (WTRU) may receive a first message from a network over a first access technology. The first message may include an indication for the WTRU to reestablish resources for one or more protocol data unit (PDU) sessions over a second access technology. The WTRU may determine that a PDU session of the one or more PDU sessions is locally deactivated by the WTRU. The WTRU may send a second message via the first access technology. The second message may include a PDU session status information element (IE) indicating the PDU session is locally deactivated such that the network releases the PDU session.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional applicationSer. No. 16/961,047, filed Jul. 9, 2020, which is the U.S. NationalStage, under 35 U.S.C. § 371, of International Application No.PCT/US2019/012705, filed Jan. 8, 2019, which claims the benefit of U.S.Provisional Application No. 62/616,687 filed Jan. 12, 2018, U.S.Provisional Application No. 62/653,817 filed Apr. 6, 2018, and U.S.Provisional Application No. 62/716,516 filed on Aug. 9, 2018, thecontents of which are hereby incorporated by reference herein.

BACKGROUND

Fifth Generation (5G) mobile networks may allow a wirelesstransmit/receive unit (WTRU) to be registered to the same Access andMobility Function (AMF) over both a Third Generation Partnership Project(3GPP) access technology and a non-3GPP access technology (e.g., WiFi)within the same public land mobile network (PLMN).

SUMMARY

A method for protocol data unit (PDU) session management over differentaccess technologies (ATs) is disclosed. A wireless transmit/receive unit(WTRU) may receive a first message from a network over a first accesstechnology. The first message may trigger an activation or reactivationof one or more PDU sessions over a second access technology. The WTRUmay determine that one or more PDU sessions have locally beendeactivated by the WTRU. The WTRU may determine that it is in a limitedservice state associated with the second access technology. The WTRU maysend a second message via the first access technology. The secondmessage may include a PDU session status information element (IE)indicating that one or more PDU sessions are locally deactivated suchthat the network releases the PDU session.

A WTRU is disclosed. The WTRU may include an antenna and a processoroperatively coupled to the antenna. The processor and the antenna may beconfigured to receive a first message from a network over a first accesstechnology. The first message may trigger an activation or reactivationof one or more PDU sessions over a second access technology. Theprocessor may be configured to determine that one or more PDU sessionsare locally deactivated. The processor may be further configured todetermine that the WTRU is in a limited service state over the secondaccess technology. The processor and the antenna may be furtherconfigured to send a second message over the first access technology.The second message may include a PDU session status information element(IE) indicating that one or more PDU sessions are locally deactivatedsuch that the network releases the PDU session.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein like reference numerals in the figures indicate like elements,and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 is a flow diagram illustrating a procedure for protocol data unit(PDU) transfer over different access technologies (ATs);

FIG. 3 is a flow diagram illustrating a procedure for PDU managementover different ATs is shown;

FIG. 4A is a flow diagram illustrating a first example of signaling forhandling race conditions;

FIG. 4B is a flow diagram illustrating a second example of signaling forhandling race conditions;

FIG. 4C is a flow diagram illustrating a third example of signaling forhandling race conditions;

FIG. 5 is a diagram illustrating an Extended Protocol Discriminator(EPD); and

FIG. 6 is a diagram illustrating using a method of updating subscriptiontype.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN 104, aCN 106, a public switched telephone network (PSTN) 108, the Internet110, and other networks 112, though it will be appreciated that thedisclosed embodiments contemplate any number of WTRUs, base stations,networks, and/or network elements. Each of the WTRUs 102 a, 102 b, 102c, 102 d may be any type of device configured to operate and/orcommunicate in a wireless environment. By way of example, the WTRUs 102a, 102 b, 102 c, 102 d, any of which may be referred to as a “station”and/or a “STA”, may be configured to transmit and/or receive wirelesssignals and may include a user equipment (UE), a mobile station, a fixedor mobile subscriber unit, a subscription-based unit, a pager, acellular telephone, a personal digital assistant (PDA), a smartphone, alaptop, a netbook, a personal computer, a wireless sensor, a hotspot orMi-Fi device, an Internet of Things (IoT) device, a watch or otherwearable, a head-mounted display (HMD), a vehicle, a drone, a medicaldevice and applications (e.g., remote surgery), an industrial device andapplications (e.g., a robot and/or other wireless devices operating inan industrial and/or an automated processing chain contexts), a consumerelectronics device, a device operating on commercial and/or industrialwireless networks, and the like. Any of the WTRUs 102 a, 102 b, 102 cand 102 d may be interchangeably referred to as a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, anaccess point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., an eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106.

The RAN 104 may be in communication with the CN 106, which may be anytype of network configured to provide voice, data, applications, and/orvoice over internet protocol (VoIP) services to one or more of the WTRUs102 a, 102 b, 102 c, 102 d. The data may have varying quality of service(QoS) requirements, such as differing throughput requirements, latencyrequirements, error tolerance requirements, reliability requirements,data throughput requirements, mobility requirements, and the like. TheCN 106 may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the CN 106 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN 104 ora different RAT. For example, in addition to being connected to the RAN104, which may be utilizing a NR radio technology, the CN 106 may alsobe in communication with another RAN (not shown) employing a GSM, UMTS,CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106 may also serve as a gateway for the WTRUs 102 a, 102 b, 102c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit 139 toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WTRU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 160 a, 160 b, 160 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 104 may also be in communication with theCN 106.

The RAN 104 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 104 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 106 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 106, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 104 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 182 may provide a control plane function for switchingbetween the RAN 104 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN106 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 106 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 104 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184 a, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 106 and the PSTN 108. In addition, the CN 106may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-ab, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

As mentioned above, a WTRU may be registered to the same AMF over both aThird Generation Partnership Project (3GPP) access technology (AT) and anon-3GPP AT (e.g., WiFi) within the same public land mobile network(PLMN). After the WTRU is registered via these access technologies, theWTRU may be in one or more of the following modes. The WTRU may be in a5GMM connected mode (CM) over both the 3GPP AT and the non-3GPP AT. TheWTRU may be in CM over the 3GPP AT and in 5GMM idle mode (IM). The WTRUmay be in IM over the 3GPP AT and CM over the non-3GPP AT. The WTRU maybe in IM over both the 3GPP AT and the non-3GPP AT.

A paging procedure may be used to trigger the WTRU to transition from IMto CM via a Service Request procedure. However, paging may only occurvia the 3GPP radio access network (RAN). Therefore, it may not bepossible for a WTRU in IM over the non-3GPP AT to be paged. However, theWTRU may be in CM over one AT but not the other. For example, when theWTRU is in CM over the 3GPP AT and in IM over the non-3GPP AT, thenetwork may need to inform the WTRU that there is downlink (DL) dataassociated with PDU sessions that have been previously established overthe non-3GPP AT. To do so, the network may use a notification procedureto inform the WTRU. The network may send the WTRU a notificationmessage. The notification message may include an indication for the WTRUto reestablish resources for one or more protocol data unit (PDU)sessions over a second access technology. The indication may be eitherimplicit or explicit.

In an example, the WTRU may receive the notification message over thenon-3GPP AT. However, because the WTRU may be in IM over the non-3GPPAT, the WTRU may respond to the notification message over the 3GPP ATand inform the network that it desires to receive the data over the 3GPPAT although the PDU sessions in question are associated with thenon-3GPP AT.

A service request message may be sent in CM over the 3GPP AT to informthe network to set up resources for the PDU sessions that the WTRU hasmoved over to the 3GPP AT. The WTRU may tell the network which PDUsessions are allowed to be moved by including an information element(IE) known as the Allowed PDU session status. If the WTRU does not wantto move any of its PDU sessions over the 3GPP AT, or has locallydeactivated one or more PDU sessions that existed on the 3GPP AT, theWTRU may respond with a notification response indicating that no userplane resources should be activated for these PDUs over the 3GPP AT.

An AMF may not be able to serve more than one Network Slice SelectionAssistance Information (NSSAI). For example, a first NSSAI maycorrespond to an isolated network slice. If a WTRU is connected to anetwork slice with a value of the first NSSAI, the WTRU may not be ableto connect to another network slice at the same time.

In an example, the notification message may also include a PDU sessionidentification (ID) corresponding to the PDU session for which there isDL data for the WTRU. The WTRU may accept the transfer of the PDU toanother access based on WTRU policy.

Furthermore, although the PDU session for which the network is sending anotification message may be desired to be transferred to the 3GPP AT,the WTRU may also want to transfer other PDU sessions although pendingDL data exits at the moment.

The notification message may be used for data related to existing PDUsessions only. However, this may limit the efficiency of the message.For example, there may be other cases for which the notification can beused to reduce paging on the radio network of the 3GPP system andtrigger a service request from the WTRU. Thus, conventional uses of thenotification may be very limited. IT may be desirable to expand the usesof the notification message to cover new cases or to apply to servicesthat are not related to existing PDU sessions.

In cases when the WTRU is in CM over the non-3GPP AT but in IM over the3GPP AT, the WTRU may have data or signaling to perform over the 3GPP AT(e.g., to perform a periodic registration update). At the same time, theWTRU's NAS entity may receive a notification message from the AMF overthe non-3GPP AT. The WTRU behavior in this case is not clear. The WTRUmay not have a set procedure to prioritize signaling and may not knowwhat to set as the establishment cause in the RRC layer.

Also, in cases when the WTRU is in CM over the non-3GPP AT but in IMover the 3GPP AT, the network may have previously experienced someoverload or congestion for data traffic related to a gateway (e.g., PGWor UPF) or related to an Access Point Name (APN) or Data Network Name(DNN). The WTRU may receive a back-off timer at the session managementlevel.

The reception of the back-off timer may prohibit the WTRU from sendingsignaling related to that specific node/network. There may be means forthe network to inform the WTRU that the congestion has been lifted atthe network side, hence allowing the WTRU to start sendingsignaling/data traffic toward that network. For this to be realized, theWTRU may need to be in CM. However, since the WTRU may be in IM over the3GPP AT and in CM over the non-3GPP AT, there may be a way to takeadvantage of this arrangement and inform the WTRU that the congestionhas been alleviated.

In both the WTRU and the network, there may be several protocol entitiesat the NAS level. When a protocol entity in the WTRU/network needs tosend a message to another “corresponding” protocol entity in theWTRU/network, the sender may use a specific (e.g., pre-defined) value ina special field in the header of the NAS message called a ProtocolDiscriminator (PD). At the receiving side, the receiver may look at thePD value in order to understand what protocol entity is addressed. ThePD field may indicate several protocol entities added with the evolutionof GPRS, UMTS and EPS. There may not be a value left to be assigned tonew 5G protocol entities. A new NAS Header may be used for 5G protocolsand an extended version of the PD, referred to as Extended ProtocolDiscriminator (EPD), may be incorporated. It may be desirable to furtherdefine the EPD.

A 5G system may have a defined procedure to update the WTRU with newparameters related to several needs, such as, for example, changing theWTRU's identity (5G GUTI) and/or Tracking Area Identity (TAI) list,providing a new service area list, and providing allowed NSSAI. However,there may be some ambiguity with the use of a WTRU configuration updatemessage. The AMF may update WTRU configuration by providing newparameter information with a command or may request the WTRU to performa new registration update with the network to update parameters. Theprocedure may be initiated by the network and may be used when the WTRUhas an established 5GMM context and is in 5GMM-CM. The AMF may require aconfirmation response in order to ensure that the parameter has beenupdated by the WTRU.

The following parameters may be supported by the generic WTRUconfiguration update procedure without the need for triggering a WTRUregistration update procedure: 5G-GUTI, TAI list, service area list,allowed NSSAI, network identity and time zone information (e.g., fullname for network, short name for network, local time zone, universaltime and local time zone, network daylight saving time), and local areadata network (LADN) information. One or more configuration parameters(e.g., policy information) may be updated by this procedure.Configuration provided by a different NF than the AMF may be covered bythis procedure or may be provided by a different NAS procedure, forexample, WTRU route selection policies (RSP) provided by a PCF.

A Mobile Initiated Connection Only (MICO) parameter may require thetriggering of the WTRU registration update procedure. The MICO mode ofoperation may be used for power saving at the WTRU. When the WTRUemploys MICO, it may deactivate its radio access capability andtransition to a sleep mode. The sleep mode may be extended and the WTRUmay “disappear” from the network. If a WTRU is configured to operate inMICO, a mechanism for the WTRU and the CN (e.g., the AMF) to inform oneanother about the usage of this mode of operation may be desirable. TheWTRU may inform the CN (e.g., AMF) of this capability during theregistration procedure. For example, the WTRU may send a parameter or IEin the registration request message informing the CN that it wants toapply the MICO mode.

This procedure may be implemented in one or more of the followingexamples. A new IE may be introduced to reflect either the capability touse a feature, such as, but not limited to MICO, that may require thenetwork to accept its usage. The new IE may be a requested feature useIE. This IE may be one octet and each bit position may reflect therequest by the WTRU to use a particular feature. For example, bitposition 0 may be the least significant bit and bit position 8 may bethe most significant bit. Bit position 0 may correspond to the MICOfeature. Thus, when the WTRU wants to use the MICO feature, it may setthe bits of this IE as “xxxxxxx1.” Thus, a value of 1 may represent arequest to use the feature and a value of 0 may represent an indicationthat the WTRU does not need to use the feature.

Extending this IE to apply to additional features, the most significantbit of this octet may be reserved to indicate if the IE is extended. Forexample, if bit position 8 has a value of 1, there may be an additionaloctet following this IE for extending it. The interpretation of thefollowing octet may be defined as needed for additional features. Forexample, if the WTRU wants to reflect the use of seven features, it mayset the bit position 8 to a value of 0. If the WTRU has more than sevenfeatures to reflect, it may set the bit position 8 to a value of 1 anduse an additional octet. The bit position 8 of the additional octet maybe reserved for the same purpose of indicating additional features. Ifthe AMF accepts or allows the use of the feature, it may return a valueof 1 for the bit position associated with the feature. Otherwise it mayset the bit position to 0. It should be noted that the particular bitpositions used above are provided as examples. Other bit positions maybe defined or reserved to reflect any of the above.

Another way for the WTRU to indicate the use of MICO may be to use a bitposition in the registration type IE. For example, the registration typeIE in the registration request message may be one octet long. It may bea type value (TV) IE. The type may reflect that this is an IE forregistration type and the value indicates the particular type ofregistration such as an initial registration or registration update. Thevalue field may be four bits long and three bits may be used to reflectthe registration type. The fourth bit may be reserved for MICO use. Forexample, bits 1001 may be interpreted as follows. The first leastsignificant bits (001) may be defined to reflect a registration type“initial registration.” The WTRU may set the MICO bit (e.g., the fourthand most significant bit of the half octet) to a value of 1 to indicatethe need to use MICO.

The AMF may use a similar procedure to reflect the result of theregistration. A registration result may also be defined with four bits.The least significant bits may reflect the type of registration that hasbeen accepted by the AMF and the fourth bit may indicate to the WTRUwhether the MICO has been allowed for use or not. When the WTRU receivesa registration result, it may verify the fourth bit position todetermine if MICO has been allowed. If the fourth bit position has avalue of 1, then the WTRU may consider MICO to have been allowed and maystart using the operation. If the fourth bit position has a value of 0,the WTRU may consider the use of MICO to be not allowed.

The MICO mode of operation may be terminated by the WTRU bytransitioning from IM to CM in conjunction with a registration procedureor a service request procedure. If the network is congested, the CN mayreject the request and provide the WTRU with a back-off timer. The WTRUmay directly apply MICO (i.e., deactivate its radio capability), run theback-off timer, and then initiate a new procedure when the back-offtimer expires.

The WTRU configuration update message may be sent to the WTRU if theWTRU is in CM. There may be no dependency on the AT over which themessage may be sent. Upon receiving the WTRU configuration updatemessage, the expected action by the WTRU may be re-registration. TheWTRU may need to re-register to the network. However, some parametersand features such as MICO are only applicable to the 3GPP AT. Aparameter that is applicable to the 3GPP AT may not be negotiated overthe non-3GPP AT. Upon reception of the WTRU configuration update messagewith a registration required indication, the WTRU may perform aregistration update after transitioning to idle mode. However, the ATthat should be used to perform the registration update may not bespecified.

Other parameters may apply to both AT equally, such as a 5G GUTI and anassociated TAI list. Receiving a new NSSAI with registration requiredmay affect both ATs since the allowed NSSAI may be associated with a TAIlist and the different ATs may have different TAI lists. A WTRU may notknow which AT to perform the registration update. The WTRU may not havethe full information regarding the actions that should be performed. Ifthe WTRU receives a new TAI list, it may not know which AT the TAI listmay be associated with. It may be desirable to avoid ambiguity at theWTRU.

New network and WTRU behavior for using the NAS notification message maybe described herein. This may include different interpretations at theWTRU and responses from the WTRU in different cases and scenarios. Inaddition, the following description may include an extension of thenotification message to optimize system signaling and not be limited tosession management signaling. New WTRU behavior for handling conflictconditions between simultaneous NAS procedures over the 3GPP AT and thenon-3GPP AT may be described below. In addition, methods by which theAMF may inform the WTRU that at least session management congestion isterminated using a notification message may be described. The WTRU mayuse this information to stop session management back-off timers. Inaddition, the following description may include a new definition for theEPD in order to support other types of mobility management messagetypes. New procedures for interpretation of the new EPD at the WTRU andnetwork may also be defined.

In addition, the following description may include methods andprocedures for minimizing ambiguity with the use of the WTRUconfiguration update message. The AMF may indicate the AT type for theparameters included in the WTRU configuration update message. The WTRUmay update the parameters of the indicated ATs with the new values. Fora new NSSAI received over the non-3GPP AT, the WTRU may start with aregistration over the 3GPP AT if no AT information is provided in theWTRU configuration update message.

The NAS notification procedure may be optimized through WTRU and networkbehavior. It should be noted that the following description assumes theWTRU is in CM over the 3GPP AT and in IM over the non-3GPP AT. However,the examples provided may apply to any of the other connection scenariosdescribed above.

The WTRU may receive, over the 3GPP AT, a notification message from thenetwork. The AMF may send a notification message to the WTRU over thenon-3GPP AT. The notification message may include an indication for theWTRU to reestablish resources for one or more protocol data unit (PDU)sessions. The indication may be either implicit or explicit.

In an example, the resources may be reestablished over a second accesstechnology. This may be because there is DL data associated with one ormore PDU sessions in 3GPP AT. The WTRU may have, for example, two PDUsthat are associated with the non-3GPP AT, PDU X and PDU Y. Although thenotification message may relate to the PDU sessions over 3GPP AT, theWTRU may also want to transfer all data for PDU Y to the 3GPP AT.Although no data is yet available for PDU Y, the WTRU may want toindicate this to the network ahead of time so that the networkassociates the other PDU with the 3GPP AT for subsequent DL data.

As such, the WTRU may still determine whether it wants other PDU IDs tobe moved to the 3GPP AT. As described above, this decision may be basedon local policies or the WTRU may display a message to a user who canchange settings and set preferences. The WTRU may then send a servicerequest and include a list of PDU IDs in the allowed PDU session statusIE.

In an example, the notification message may also include one or more PDUsession IDs associated with the non-3GPP AT for which the network cantransfer the data towards the 3GPP AT. The WTRU may verify the receivedPDU session ID (PDU ID) against its local policies. The WTRU may havepolicies that indicate which PDU IDs are allowed to be transferred overa target access technology. The WTRU may verify if the received PDU IDis permitted to be transferred over a different target accesstechnology. The WTRU may further verify details in its policies to makesuch a determination. Policy details may include, for example, time,location, and whether the PDU session is associated with a LADN. If anyof the PDU IDs in the notification message are subject to transfer toanother access, and the WTRU may determine to do so, the WTRU may send aservice request message to the network. The service request message mayinclude the list of PDU IDs that the WTRU desires to transfer to the3GPP AT. The list of PDU IDs may be included in the allowed PDU sessionstatus IE. In other words, the WTRU may use the received PDU IDs toverify against its local policies and determine which PDU IDs may betransferred to the 3GPP AT.

The WTRU may have uplink data to send related to at least one PDU IDassociated with the non-3GPP AT. However, the WTRU may not be incoverage of the non-3GPP AT or the WTRU may have policies to move thePDU sessions to the 3GPP AT. In this case, although the WTRU is notpaged, the WTRU may send a service request and may include the allowedPDU session status IE to indicate to the network that it desires totransfer the indicated PDU sessions from the non-3GPP AT to the 3GPP AT.

The WTRU may include a NAS level establishment cause in the servicerequest message to inform the AMF why the service request is being sent.The details of this NAS level establishment cause may be defined inadditional details below. The WTRU may include a NAS level establishmentcause or other type of information that explains why it is sending aservice request message and/or a service type that the WTRU would liketo request. For example, the WTRU may include a service type set to“transfer PDU from non-3GPP to 3GPP” to indicate that the WTRU desiresto transfer at least one PDU session (e.g., identified by the allowedPDU session status IE) from the non-3GPP AT to the 3GPP AT.

The AMF may receive a service request message (or other NAS message)with the allowed PDU session status IE that identifies at least one PDUID that the WTRU desires to transfer from the non-3GPP AT to the 3GPPAT. The WTRU may also include a NAS level establishment cause or otherinformation, such as a service type that indicates “transfer PDU fromnon-3GPP to 3GPP” as described above. The AMF may verify the PDU ID andmay determine that at least one PDU ID has no DL data pending. The AMFbehavior may be different depending on whether the WTRU is initiatingthe service request by itself or if it is responding to paging or anotification message.

The AMF may determine if the WTRU is initiating the service request byitself (i.e., the message is not a response to paging or a notificationmessage) by verifying that the establishment cause is received from thelower layers (i.e., the RAN). Alternatively, the AMF may determine thisby verifying the NAS level establishment cause or the service type asdescribed above. If the AMF may determine that the WTRU is initiatingthe service request by itself, the AMF may proceed with the procedureand inform the SMF to change the associated AT from non-3GPP to 3GPP.The SMF may receive a request, for example using the defined referencepoints (e.g., Nsmf_PDUSession_UpdateSMContext Request), to set upresources for a PDU session identified by a PDU ID. The request may alsocontain an AT type. If the AT type is not the same as the AT type in theWTRU's session management (SM) context, the SMF may update the AT typeto reflect the received AT type from the AMF. The SMF may take otheractions and inform other network nodes about the updated AT associatedwith the identified PDU session. For example, the SMF may inform thePCRF about this change using the appropriate reference point.

If the AMF may determine that the WTRU is initiating the request byitself and the AMF receives at least one PDU session for which the WTRUdesires to transfer from the non-3GPP AT to the 3GPP AT, the AMF mayproceed with the service request procedure so that user plane resourcesand connections are set up for the WTRU. If accepted by the AMF, the AMFmay respond to the WTRU with a service accept message and indicate thePDU session IDs for which the AMF has accepted to setup user planeresources.

If the AMF pages the WTRU over the 3GPP AT for data related to non-3GPPAT PDU sessions, and the WTRU has included at least one PDU IDassociated with the non-3GPP AT which it wants to move to the 3GPP AT,the AMF may take any of the following actions described herein.

The AMF may verify if the provided PDU ID is associated with DL pendingdata. If the PDU ID is associated with DL pending data, the AMF may setup the resources as described above. If the PDU ID is associated with DLpending data (i.e., if there is a PDU ID in the service request messagefor which there is no DL data), the AMF may take any of the followingactions.

The AMF may reject the service request message. The AMF may send aservice reject message to the WTRU, which may include a cause code toindicate to the WTRU that there is no pending DL data at the moment. TheAMF may also indicate whether the PDU connection is now considered to beassociated with the 3GPP AT or if it is still associated with thenon-3GPP AT. The AMF may have preferences or policies to determine this.Alternatively, as discussed above, the WTRU may include a preference inthe service request message, where, for each PDU ID, the WTRU may informthe network whether it wants to associate the PDU with a different AT.The WTRU may use its local policies to determine this. When the AMFdetermines that a PDU session referenced by a PDU ID may be associatedwith the 3GPP AT, the AMF may include the PDU ID and the associated AT.The WTRU may then update its local information to indicate that the PDUID is associated with a different AT, whose type may be indicated in theNAS message (e.g., service reject message).

The AMF may accept the service request message and include a cause codeto indicate that the resources are not set up intentionally (e.g., dueto unavailability of pending DL data as described above). The AMF mayalso include additional information in the NAS message to inform theWTRU that the PDU sessions, identified by PDU IDs, have been consideredto be transferred to, or are now associated with, another AT. The WTRUmay receive a service reject message with a new cause code indicatingthat a list of PDU IDs have no resources set up for them. In addition,the message may indicate that the PDU session, referenced by a PDU ID,is not associated with another AT. The WTRU may update its local SMcontext to reflect the new AT that is now associated with each of thePDU session identified by the PDU ID.

The WTRU may receive a service accept message in response to sending aservice request message indicating a list of PDU IDs for which the WTRUwants to transfer to or associate with a different AT. The WTRU mayexpect that resources will be set up due to the reception of the serviceaccept message. However, if the resources are not set up (e.g., if theRRC layer in the WTRU did not receive a configuration message to setupradio resources), the WTRU may assume that there is a failure eitherlocally or at the network.

To avoid the WTRU considering the procedure as unsuccessful, the WTRUmay use the provided information in the service accept message todetermine if the service request procedure is successful. The WTRU mayuse any of the IEs described above that may be included in the NASmessage by the AMF. For example, the WTRU may use a cause code with avalue that indicates that the network has intentionally not set up userplane resources as a means to determine that the service requestprocedure is successful although no user plane resources or radioresources for the user plane are set up.

Alternatively, the WTRU may use a cause code or additional informationmay indicate that a list of PDU sessions, referenced by PDU IDs, are nowassociated with another AT as a means to consider the successfulcompletion of the service request procedure although no radio resourceswere setup. The WTRU may update its local context to reflect that thePDU sessions identified by PDU IDs are now associated with a differentAT.

As described above, the proposals above can occur over any AT and anyconnection mode. It should be noted that the WTRU may send a servicerequest message instead of a notification response message and mayinclude any or all of the information described herein. The proceduresfor sending a notification response message by the WTRU may apply in asimilar manner should the WTRU send a service request message instead.

Referring now to FIG. 2 , a flow diagram illustrating a procedure forPDU transfer over different ATs is shown. FIG. 2 shows how some of theproposals described above may be used. The procedure for PDU transfermay include a WTRU 202, a 3GPP RAN 204, a non-3GPP 206 AN, an AMF 208,and an SMF 210.

As shown in step 0, the WTRU 202 may be in CM in the 3GPP AT and in IMin the non-3GPP AT. The WTRU 202 may have a PDU A associated with the3GPP AT and may have a PDU B and PDU C associated with the non-3GPP AT.

In step 1, the WTRU 202 may receive a notification message from the AMF208. The notification message may include an indication for the WTRU toreestablish resources for one or more protocol data unit (PDU) sessions.The indication may be either implicit or explicit. In an example, theresources may be reestablished over a second access technology. In step2, the WTRU 202 may use local policies or preferences to determine ifone or more PDUs should be moved over to the 3GPP AT.

In step 3, the WTRU 202 may send a service request message to the AMF208. The service request message may include the allowed PDU sessionstatus (e.g., PDU B and/or PDU C). The service request message may alsoinclude additional information indicating permanent transfer of PDU C tothe 3GPP AT.

In step 4, the AMF 208 may determine which PDUs can be transferred tothe 3GPP AT.

In step 5, the AMF 208 may send an updated context to the SMF 210. Theupdated context may include access information for one or more of PDU Band PDU C.

In step 6, the AMF 208 may send a service accept message to the WTRU202. The service accept message may include additional informationindicating permanent transfer of PDU C to the 3GPP AT.

In step 7, the WTRU 202 may use the information received in the serviceaccept message to update the SM context to reflect the PDU C beingtransferred to the 3GPP AT.

The WTRU 202 may determine to not transfer any PDU sessions regardlessof whether there is pending DL data or not. The WTRU 202 may havepreferences to temporarily reject a PDU session transfer. In this case,based on WTRU policies, the WTRU 202 send a notification responsemessage to the network and indicate that the WTRU 202 temporarilyrejects the transfer of the PDU session. The WTRU 202 may include a newcause code for each PDU session, referenced by a PDU ID, indicating thatthe WTRU 202 does not want to transfer to another AT. Alternatively, theWTRU 202 may have a policy to not transfer the PDU to another AT. Inthis case, the WTRU 202 may include a cause code indicating so. The WTRU202 may also send the service request message instead of thenotification response message. The WTRU 202 may also indicate a timewindow during which future requests for PDU transfer across ATs arepermitted or are not permitted.

The AMF 208 may receive a NAS message (e.g., a notification responsemessage or a service request message) with information indicating thatsome PDU sessions, referenced by PDU IDs, may not be transferred toanother AT. The cause code or information in the NAS message mayindicate a temporary rejection or permanent rejection. The AMF 208 maysend a notification message to the SMF 210 to indicate if this is apermanent or temporary rejection. The AMF 208 may include a time atwhich the SMF 210 may request such a transfer or not. The SMF 210 mayupdate its local information accordingly.

Referring now to FIG. 3 , a flow diagram illustrating a procedure forPDU management over different ATs is shown. The procedure for PDUtransfer may include a WTRU 302, a 3GPP RAN 304, a non-3GPP AN 306, anAMF 308, and an SMF 310.

As shown in step 0, the WTRU 302 may be a limited state in the 3GPP ATand in CM in the non-3GPP AT. The WTRU 302 may have a PDU A associatedwith the 3GPP AT and may have a PDU B and PDU C associated with thenon-3GPP AT.

In step 1, the WTRU 302 may receive a notification message from the AMF308. The notification message may include an indication for the WTRU toreestablish resources for one or more protocol data unit (PDU) sessions.In an example, the resources may be reestablished over a second accesstechnology. In an example, the AMF 308 may start a timer. In step 2, theWTRU 302 may use local policies or preferences to determine if otherPDUs should be moved over to the 3GPP AT.

In step 3, the WTRU 302 may send a notification response message to theAMF 308. The notification response message may include a PDU sessionstatus IE. The notification response message may be a NAS message. Uponreceipt of the notification response message, the AMF 308 may stop thetimer.

In step 4, the AMF 308 may determine which PDUs may be deleted.

In step 5, the AMF 308 may send an updated context to the SMF 310.

If the WTRU 302 is in CM for the 3GPP AT and in IM for the non-3GPP AT,or in CM for the non-3GPP AT and in IM for the 3GPP AT, the WTRU 302 mayhave several PDU sessions. The WTRU 302 may have locally deactivatedsome PDU sessions without signaling with the network. If the WTRU 302receives a notification message with a list of PDUs that the network haspending DL data for, or the network wants to transfer to another AT, theWTRU 302 may verify if the PDU sessions, referenced by the PDU IDs, arestill active. If not, the WTRU 302 may send a notification responsemessage and include a PDU session status IE to indicate that some PDUsessions have been deactivated by the WTRU 302. Alternatively, the WTRU302 may send the service request message instead of the notificationresponse message and indicate that the PDU sessions have been locallydeactivated. The AMF 308 may then initiate the deactivation of thecorresponding PDU sessions towards the SMF 310.

Accordingly, the WTRU 302 may send a notification response message andindicate that PDU sessions have been deactivated. Alternatively, if theWTRU 302 receives a paging request over the 3GPP AT with an access typeindicating non-3GPP access, and the WTRU 302 has deactivated its PDUsessions that were associated with the non-3GPP AT, the WTRU 3023 maysend a service request message and indicate that there are no PDUsessions active in the WTRU 302 that are associated with the non-3GPPAT. A new IE may be used to indicate this, or the PDU session status IEmay be used.

The notification message may be extended to use beyond a PDU sessiontransfer, which may be describe in additional detail herein. The use ofthe notification message may be extended to make the overall system moreefficient. For example, if the WTRU is in CM over the non-3GPP AT and inIM over the 3GPP AT, the AMF may have policies to deliver Short MessageService (SMS) over the 3GPP AT. In order to avoid paging, and thesignaling in the system due to the paging, the AMF may send anotification message to the WTRU over the non-3GPP AT to indicate theneed to establish the NAS connection over 3GPP even though the reason isnot for user plane data. The AMF may include an indication in thenotification message to inform the WTRU whether the message is been sentfor particular services that are not necessarily related to user planedata. User plane data may refer to any type of data that does not goover the control plane and may be IP or non-IP.

In another scenario, the WTRU may be in a non-allowed tracking area(i.e., it is camped on a cell whose tracking area identity is determinedto be a non-allowed tracking area identity) and the WTRU may be in thestate “5GMM-REGISTERED.NON-ALLOWED-SERVICE.” In this state, the WTRU maynot perform the mobility and periodic registration update procedure withan uplink data status IE except for emergency services. Furthermore, theWTRU may not be allowed to initiate the service request procedure.

However, if the WTRU is in CM over the non-3GPP AT and receives anotification message, the WTRU may send a notification response toindicate to the network that it cannot re-activate its user planeresources over the 3GPP AT. The WTRU may also indicate a reason for whythis is not possible (i.e., the WTRU may inform the network why itcannot send the service request message). The WTRU may send an IE thatcan be defined and included in the NAS message (e.g., the notificationresponse) that the WTRU is in a non-allowed area. Other cause codes orIEs may also be defined to reflect existing reasons (e.g., the WTRU isin a limited state or the WTRU is searching for PLMN) or new reasons whythis may not be possible for the WTRU to reactive its user planeresources over the 3GPP AT.

As such, if the WTRU is in CM over the non-3GPP AT and in IM over the3GPP AT and the WTRU's 3GPP state is“5GMM-REGISTERED.NON-ALLOWED-SERVICE,” the WTRU may send a notificationresponse message (or any NAS reject message that may be defined) if theWTRU receives a notification with a list of PDU IDs related to 3GPPaccess or a notification with any other indication (e.g., for networktriggered signaling or SMS) that the WTRU should set up its NASconnection over the 3GPP AT.

The methods and procedures described below may be used to handle raceconditions for NAS procedures over the 3GPP AT and the non-3GPP AT. AWTRU may be in CM over the non-3GPP AT and in IM over the 3GPP AT. TheWTRU may run a periodic registration timer to guard periodicregistration updates over the 3GPP AT. The periodic registration may notbe supported over the non-3GPP AT. In one scenario, the WTRU may receivea notification message for pending DL data corresponding to PDUsessions, identified by PDU IDs, that are associated with the 3GPP AT.The WTRU may receive this notification message a few seconds ormilliseconds away before performing a registration update (i.e., itsperiodic registration timer may be very close to expiring). By the timethe notification message is received, the WTRU may also have to performa periodic registration as described above. In this case, the WTRU maybe faced with a race condition. For example, the notification messagemay trigger a service request and at the same time the periodicregistration timer of the WTRU may have expired.

The WTRU may prioritize the registration update procedure instead of theservice request. Upon receipt of a notification message (over thenon-3GPP AT) with a list of PDU IDs associated with the 3GPP AT, theWTRU may verify if the PDU sessions are still active in the WTRU. If thePDU sessions are active, the WTRU may send the registration updatemessage over the 3GPP AT and include the uplink data status IE. The WTRUmay set the values of the uplink data status IE to include at least thePDU IDs that were present in the notification message. The WTRU may alsoinclude other PDU IDs in the uplink data status IE if it has uplink datato send.

Another scenario for race conditions may arises if the WTRU is in IMover the 3GPP AT and in IM over the non-3GPP AT. The WTRU may receive apaging message with the AT type set to non-3GPP, which may indicate thatthe paging message is triggered by pending DL data for PDU sessionsassociated with the non-3GPP AT. As described above, the WTRU's periodicregistration timer may be about to expire or may have just expired whenthe WTRU receives the paging message. In this case, the WTRU may alsoprioritize performing a registration update over the service request.Moreover, the WTRU may include the allowed PDU session status IE in theregistration message.

These procedures may also be performed when the WTRU is in the state“ATTEMPTING-REGISTRATION-UPDATE” and the WTRU receives a paging message.In this case, the WTRU may send the registration request message and mayinclude the allowed PDU session status IE in the periodic registrationmessage if the WTRU receives a paging message with the AT type set tonon-3GPP.

The procedures also apply for any other triggers or conditions thatwould require a registration request to be sent by the WTRU and are notlimited to the case of the periodic registration. For example, the WTRUmay perform a registration update to other parameters related to otherfeatures such as, but not limited to, MICO operation and the use ofnetwork slicing. Another example of a trigger may be the WTRU entering anew tracking area list, needing to perform a registration update, andreceiving a notification message over the non-3GPP AT.

When the AMF sends a paging message, it may start a timer to guard thetime during which a response (i.e., a service request) is expected fromthe WTRU. In the example described above, the reception of theregistration request message from the WTRU may cause the AMF to stop thetimer. Alternatively, reception of the service request message with theallowed PDU session IE may cause the AMF to stop the timer. If there isno allowed PDU session IE in the registration update message, the AMFmay check if a PDU status IE is included. If the PDU status IE includesPDU IDs corresponding to the non-3GPP AT for which the AMF triggered thepaging (e.g., due to pending DL data associated with the PDU IDs), theAMF may use this as the trigger to stop the timer. The AMF may considerthe paging procedure as successful.

Similarly, when the AMF sends a notification message and starts a timerto guard the response from the WTRU, the AMF may use a receivedregistration request message, as described above, to stop the timer. TheAMF may consider the notification procedure as successful.

In cases where the WTRU sends the registration request message, asdescribed above, the AMF may perform one or more of the followingactions. The AMF may take all the actions for reception of the servicerequest message or notification response message (if applicable) asdescribed above. For example, the AMF may verify if the included allowedPDU status IE contains PDU IDs that do not have pending DL data but theWTRU wants to transfer to the 3GPP AT. The AMF may determine if thetransfer is allowed based on WTRU subscription and/or local policies. Ifthe transfer is accepted, the AMF may inform the SMF (associated witheach PDU ID) that the AT has changed to the 3GPP AT. The SMF may updatethe context for the WTRU to reflect that the AT associated with the PDUis now 3GPP.

The AMF may also include one or more of the IEs described above in theregistration accept message. For example, the registration acceptmessage may include information to inform the WTRU if other PDU sessionsreferenced by a PDU ID are considered to be permanently associated withthe 3GPP AT even if no resources are set up for these PDUs. The WTRU mayuse the included information in the registration accept message in thesame manner proposed for the reception of the information in the serviceaccept message or the service reject message as described above. Forexample, the WTRU may receive a registration accept message withinformation that at least one PDU is now associated with the 3GPP AT.The WTRU may use this information to update its session managementcontext such that the indicated PDU sessions are now associated with the3GPP AT.

It should be noted that these procedures may be applied in anycombination over any AT. The specific AT are used as examples only andare not intended to limit the procedure to the specific AT mentioned.The AT may be switched for the procedures described above.

Referring now to FIGS. 4A-4C, flow diagrams illustrating signaling forhandling race conditions is shown. FIG. 4A shows a first example ofsignaling used in the procedures described above. FIG. 4B shows a secondexample of signaling used in the procedures described above. FIG. 4Cshows a third example of signaling used in the procedures describedabove. The signaling procedure may include may include a WTRU 402, a3GPP RAN 404, a non-3GPP AN 406, and an AMF 408.

As shown in FIG. 4A, in step 1a, the AMF 408 may send a notification tothe WTRU 402. In an example, the notification may include a list of PDUIDs for the 3GPP AT through the non-3GPP AT. Additionally oralternatively, in step 1b the AMF may send a paging with an access typeof non 3GPP through the 3GPP AT. In step 2, the WTRU 402 may check ifone or more PDUs are active. In step 3a, the WTRU 402 may send anotification response to the AMF 408 with a PDU status IE. Additionallyor alternatively, in step 3b the WTRU 402 may send a service request tothe AMF 408 with the PDU status IE.

As shown in FIG. 4B, in step 1 the AMF 408 may send a notification tothe WTRU 402. In an example, the notification may include a list of PDUIDs for the 3GPP AT through the non-3GPP AT. In step 2, the WTRU 402 maytrigger a TAU. In step 3, the WTRU 402 may send a registration requestto the AMF 408. The registration request may include an allowed PDU IE.The WTRU 402 may include PDU IDs based on local policies. In step 4, theAMF 408 may stop a notification timer. In step 5, the AMF 408 may verifyif the PDUs in the registration request can be transferred to the 3GPPAT. In step 6, the AMF 408 may send a registration accept message to theWTRU 402. The registration accept message may include information aboutwhich PDUs have been transferred to the 3GPP AT even if no user planeresources are set up.

In FIG. 4C, in step 1 the AMF 408 may send a UCU message to the WTRU 402through the non-3GPP AT. The UCU message may include one or more allowedNSSAI and AT type. In step 2, the WTRU 402 may go to IM in the non-3GPPAT. In step 3, the WTRU may send a registration request message to theAMF through the 3GPP AT. In step 4, the WTRU 402 may performregistration on the non-3GPP AT.

The following procedures may address congestion at the WTRU. Uponreception of an indication from the SMF that congestion related to aspecific DNN has been lifted, the AMF may send a notification message tothe WTRU over the non-3GPP AT. The notification message may carry anindicator (e.g., an IE) that points to the previously congested network.The notification message may include an explicit indicator that thecongestion is terminated, or it may include PDU IDs and additionalinformation such as, but not limited to, DNN and/or S-NSSAI.

The WTRU may receive a notification message that contains at least alist of PDU IDs, and optionally DNN and/or S-NSSAI. The notificationmessage may also include an explicit indication about the termination ofcongestion per PDU ID. Upon reception of this message, the WTRU mayverify if it has any back-off timers running per PDU ID, DNN, S-NSSAI,or any combination. If the WTRU has a corresponding session managementback-off timer running for at least any of the PDU IDs in thenotification message, the WTRU may stop the corresponding back-off timerand consider that the session management towards at least the SMF, theDNN, the S-NSSAI, or a combination thereof is over. The WTRU may theninitiate session management signaling towards the SMF (identified by thePDU ID, DNN, S-NSSAI, or a combination thereof).

The notification message may also be used by the AMF to inform the WTRUof a start of congestion control for either mobility management orsession management. When it determines that the AMF or SMF is congested,the AMF may send the notification message and indicate that congestioncontrol should be applied by the WTRU for mobility management and/orsession management signaling. The AMF may include a correspondingmobility management back-off timer and/or session management timer. Thelatter may be related to SMF congestion, DNN congestion, S-NSSAIcongestion, or a combination thereof. Upon reception of the notificationmessage, the WTRU may start the corresponding back-off timer (i.e.,mobility management and/or session management) and may refrain fromsending messages to the AMF and/or SMF accordingly.

The procedures described above to indicate to the WTRU that congestionis over for session management level may also be used for the mobilitymanagement level. For example, the notification message may be sent tothe WTRU over the non-3GPP AT with an explicit indication thatcongestion control at the mobility management layer is terminated. TheWTRU may use this as an indication to stop the mobility managementback-off timer.

If congestion is severe, the CN may inform the RAN to back-off devicesupon their request for an RRC connection. The RAN node (e.g., gNB) mayreject RRC connection request messages from WTRUs and may provide themwith a so called extended wait time (EXT). The EXT may act as a back-offtimer. If the WTRU receives the EXT from the RAN node, it may directlyapply the MICO mode, as described above, and only attempt to transitionfrom IM to CM mode once the timer expires.

As described above, a new field may be used for the EPD. Table 1 showslegacy values for the PD, which may be currently used.

TABLE 1 Protocol Discriminator Values Bits 4321 Indication 0 0 0 0 groupcall control 0 0 0 1 broadcast call control 0 0 1 0 EPS sessionmanagement messages 0 0 1 1 call control; call related SS messages 0 1 00 GPRS Transparent Transport Protocol (GTTP) 0 1 0 1 mobility managementmessages 0 1 1 0 radio resources management messages 0 1 1 1 EPSmobility management messages 1 0 0 0 GPRS mobility management messages 10 0 1 SMS messages 1 0 1 0 GPRS session management messages 1 0 1 1 noncall related SS messages 1 1 0 0 Location services specified in 3GPP TS44.071 1 1 1 0 reserved for extension of the PD to one octet length 1 11 1 used by tests procedures described in 3GPP TS 44.014, 3GPP TS 34.109and 3GPP TS 36.509

The code-point “1110” may be reserved for the extension of the PD fieldto one octet. This means that a receiver, upon reading “1110”,understands that the actual value of the PD (or EPD in this case) may berealized in the whole octet.

Conventional 5G systems may have two NAS protocol entities, the 5GMM andthe 5GSM. Only two code-points may need to be allocated for these twoprotocol entities. However, there are a total of 16 availablevalues/code-points that may need to be defined.

The value “zero” may not be used and may instead refer to an error orabnormal situation. The reason behind this proposal is that certain L3NAS messages have historically had a “Skip Indicator” that was allzeroes and resided in the left half octet of the first octet. Examplesof such protocols would be MM, GMM, EMM.

Two distinct values may be assigned to the existing 5G NAS protocols(i.e., 5GMM and 5GSM). For example, a value of “0001 1110” may be usedfor 5GMM and a value of “0010 1110” may be used for 5GSM. The actual EPDvalue for 5GMM may be “30” and the actual value for 5GSM may be “46.” Itshould be noted that other values may be used to refer to 5GMM or 5GSMprotocols. For example, if bits 8 to 5 have a value of “1110,” the WTRUand/or the AMF may consider the EPD to be further extended by at leastone additional octet. The WTRU and/or AMF may then process theadditional octet to determine the protocol. The additional octet mayintroduce 256 new values. The values may start at “0” (i.e., all bitsare zero), or the values may start with 256 plus the value of theprevious octet having bit positions as follows: “11101110” (decimalvalue of 238). The new octet may have new reserved values that may bedefined as needed.

Referring now to FIG. 5 , a diagram illustrating an EPD is shown. Acode-point may be reserved for future use. For example, the code-pointmay be used to point out the usage of another mechanism or even anotherprotocol. This may be done by either using a value in the entire EPDoctet or by using only one or more bits. For the latter case, the mostsignificant bit of the octet (i.e. bit number 8, shown as “X” in theFIG. 5 ) may serve this purpose. If this bit is a zero, the EPD mayrefer to 5G NAS protocol entities. However, if the bit value changes toa “1,” a different protocol may be used and the interpretation of thefollowing octets may be different.

Additional information may be provided in the WTRU configuration updatemessage to ensure correct WTRU behavior. As described above, the WTRUconfiguration update message may lack certain information such that,upon reception, the WTRU behavior may not be as expected or may not becomplete. In order to remove ambiguity at the WTRU side so that acorrect procedure is run over the correct AT, WTRU may treat the WTRUconfiguration update message as described below.

In an example, the network may send the WTRU configuration updatemessage over different ATs to update parameters that are specific tothat AT. If the WTRU is registered over the 3GPP AT and the networkwants to provide updated parameters to the WTRU related to features thatare only available on the 3GPP AT (e.g., MICO, LADN, new service area,NSSAI), the AMF may send the WTRU configuration update over the 3GPP AT.As such, the WTRU may respond over that same AT. If the WTRU is in CMover the 3GPP AT, the AMF may send the WTRU configuration update messageto the WTRU. However, if the WTRU is in IM over the 3GPP AT, the AMF mayfirst page the WTRU and then execute the WTRU configuration updateprocedure towards the WTRU.

Alternatively, if the WTRU is also registered over the non-3GPP AT andthe WTRU is in CM over the non-3GPP AT but in IM over the 3GPP AT, theAMF may first send a notification message over the non-3GPP AT andindicate to the WTRU to establish its NAS connection over the 3GPP ATfor the purpose of signaling. The notification message may contain newIE to indicate to the WTRU that it has to establish its NAS connectionover the 3GPP AT. Alternatively, the indication from the AMF in the WTRUconfiguration update message may explicitly inform the WTRU (e.g., vianew IEs) that the NAS connection has to be established with a servicerequest or a registration request message.

If the WTRU is in CM over the non-3GPP AT and WTRU configuration updatemessage over the non-3GPP AT with new parameters (e.g., GUTI, TAI,and/or NSSAI), the WTRU may consider the parameters to only affect thenon-3GPP AT. As such, the WTRU may update its non-3GPP parameters withthe parameters received over the non-3GPP AT. For example, if the WTRUreceives a new TAI, it may consider a previous TAI received over thenon-3GPP AT as invalid and use the new received TAI as the most up todate and valid TAI. The WTRU may also update its 5G GUTI with the newvalue. However, if the WTRU is also registered to the same AMF withinthe same PLMN, the WTRU may also consider the new 5G GUTI to be validfor both ATs.

Another way to ensure that the WTRU knows which parameters to use perAT, may be to send the WTRU configuration update message on either ATand include additional information to tell the WTRU to which AT thereceived parameters apply.

If the WTRU receives a WTRU configuration update message over aparticular AT, and the WTRU configuration update message containsparameters for the same or different AT over which the message wasreceived, the WTRU may first send a configuration update completemessage over the same AT over which the WTRU configuration updatemessage was received. Alternatively, the WTRU may have policies to use adifferent AT to send the configuration update complete message.

The WTRU may receive a WTRU configuration update message over thenon-3GPP AT that indicates that new MICO parameters need to benegotiated or that the WTRU configuration update message was sent due toa MICO parameter update. A registration required indication may beprovided in the message. If the WTRU is in IM over the 3GPP AT, the WTRUmay remain in CM over the non-3GPP AT but may initiate a registrationprocedure (i.e., send a registration request message) to the network inorder to negotiate new MICO parameters.

If the AMF wants to send a new 5G GUTI and TAI list to the WTRU, the AMFmay inform the WTRU if the TAI is applicable to the 3GPP AT or thenon-3GPP AT. This information may be included regardless of the AT overwhich the WTRU configuration update message is sent. The AMF may alsosend a different AT indication per TAI, or the TAI may be sent per AT.The TAI field may be defined such that it has an associated AT type. Theindication of TAI association to an AT type may be important since theAMF may want to change the parameters related to one AT but not theother. Similarly, the AMF may inform the WTRU about each parameter'sassociation to an AT whenever applicable. For example, for every list ofNSSAI, the AMF may inform the WTRU whether the new NSSAI provided in aWTRU configuration update is applicable to one AT or both.

When the WTRU receives a WTRU configuration update message with a new 5GGUTI and/or TAI, the WTRU may verify what type of AT the TAI listapplies to or affects. The WTRU may update the TAI list of the indicatedAT accordingly. The WTRU may receive more than one TAI list and AT typeIE. The WTRU may use the provided TAI list, per AT, to represent thevalid TAI list for the WTRU per AT such that the previous TAI list perAT may be considered invalid by the WTRU.

When the WTRU receives a new allowed NSSAI, the WTRU may verify the ATthat is associated with the new NSSAI. The WTRU may update its list ofallowed NSSAI associated with the indicated AT accordingly.

The WTRU configuration update message may contain a new allowed NSSAIand may also indicate a need for registration by the WTRU. If the WTRUreceives a new NSSAI over the non-3GPP AT, the WTRU may verify if themessage contains a new list of allowed NSSAI. If the message doescontain a new list of allowed NSSAI, the WTRU may verify the ATassociated to the new list and may update the list accordingly.Moreover, if the WTRU configuration update indicates that a registrationis required, then the WTRU may perform a registration on the indicatedAT without transitioning to IM on the non-3GPP AT. The WTRU may remainin CM over the non-3GPP AT.

If the WTRU configuration update message contains a new allowed NSSAIand a registration required indication, but does not include an AT type,the WTRU may perform one or more of the following actions. The WTRU mayconsider the 5G GUTI as invalid for both ATs. The WTRU may locallydeactivate all its PDU connections that are associated with both the3GPP AT and the non-3GPP AT. The WTRU may send a registration requestover the 3GPP AT and may provide its SUPI and the new allowed NSSAI tothe lower layer.

After successful registration on the 3GPP AT, the WTRU may re-registerover the non-3GPP AT and may use the 5G GUTI that was obtained over the3GPP AT. The WTRU may have policies to register over the non-3GPP ATfirst and then register with the 3GPP AT later. For example, the WTRUmay first register over the AT over which the WTRU configuration updatemessage was received.

The WTRU may establish its PDU sessions over each of the ATs as needed.The PDU sessions may be established based on the allowed NSSAI and WTRUpolicy.

The AMF may have policies to use a particular AT type for Short SMSsignaling. For example, the AMF may prefer use the 3GPP AT for SMS basedon a local policy. This policy may change over time and may not bestatic. The AMF may determine the preferred AT to use for SMS based onone or more of local policies, subscription information, andsubscription information updates from the Unified Data Management (UDM)function. The AMF may inform the WTRU about the new AT that should beused. For a WTRU that is already registered, the AMF may first page theWTRU if the WTRU is in idle mode. The AMF may use the WTRU configurationupdate message to indicate the preferred AT to use for SMS. The WTRUconfiguration update may contain one or more IEs indicating the affectedservice (e.g. SMS or location service) and the AT to use. Alternatively,if the WTRU is already in CN, either over the 3GPP AT or the non-3GPPAT, the AMF may send the WTRU configuration update message with theproposed information, which may include the affected service (e.g. SMS)and the preferred AT to use for the service.

The WTRU may receive a WTRU configuration update message with updatedparameters and information. The WTRU may verify only the indicated oraffected services and the associated preferred access technology.

The AMF may use the WTRU configuration update command procedure toupdate the slice coexistence parameters at the WTRU. When the slicecoexistence information changes at the network side (e.g., due tonetwork configuration), the AMF may be notified by one of the networkfunctions, such as a Network Slice Selection Function (NSSF), a UnifiedData Management (UDM) function, and a Policy Control Function (PCF), oran operations and maintenance (O&M) system. The AMF may then send thenew slice coexistence information to the WTRU in the WTRU configurationcommand message.

The AMF may send the WTRU configuration update message over both AT ifthe WTRU is connected simultaneously to 3GPP AT and non-3GPP AT. Thecoexistence information may affect the NSSAIs that are configured orallowed in both the 3GPP AT and the non-3GPP AT. The AMF may send thisinformation on the AT having NSSAIs that are effected by change in slicecoexistence information. Alternatively, the AMF may send the WTRUconfiguration update message on either the 3GPP AT or the non-3GPP AT,and may include an AT value to which the new slice coexistenceinformation pertains to.

The slice coexistence information sent by the AMF may include one ormore single NSSAIs (S-NSSAIs) that belong to isolated slices or one ormore S-NSSAIs that cannot be included with the requested NSSAI.

A WTRU may perform one or more of the following actions upon receiving aWTRU configuration update message with updated slice coexistenceinformation. The WTRU may compare the received slice coexistenceinformation with existing coexistence information to determine if theallowed NSSAI is still valid. If the allowed NSSAI is no longer valid(e.g., because it contains an NSSAI that is now marked as isolated inthe new slice coexistence information), then the WTRU may perform aregistration update procedure (e.g., a mobility type registrationupdate). The WTRU may delete the existing slice coexistence informationand replace it with the new slice coexistence information. When the WTRUperforms the re-registration procedure, the WTRU may take into theaccount the received coexistence information to determine the requestedNSSAI. The requested NSSAI may be included in the registration requestmessage to the AMF. The WTRU may not include a received isolated S-NSSAIin the requested NSSAI.

With the introduction of an IP Multimedia Subsystem (IMS), SMS messagemay be sent over IP networks. The SMS messages may be exchanged in theUser Plane and the routing may be done by means of IP-packets. Thisversion of SMS may be referred to as “SMS over IP” or “SMS over IMS.” Inorder to support SMS over IP/IMS, the network operator may need toenhance their infrastructure by means of a specific gateway, called anIP-SM-GW.

With the introduction of 5G networks, the operator may have more freedomfor the choice of the network. This means that, during the registrationphase, the WTRU and the network may negotiate about how the SMS issupported and realized. As an example, the network may inform the WTRUthat the legacy SMS over NAS shall not be used, which means that theonly option of sending/receiving SMS for the WTRU would be SMS overIP/IMS.

When it comes to the actual transfer of SMS over NAS, the correspondingsignaling protocols may be in the WTRU and the SMS Function (SMSF) onthe core network side. At the NAS level, SMS messages and theircorresponding acknowledgements may be exchanged between the WTRU andSMSF.

In 5G systems, Cellular Internet of Things (CIoT) small data may bedelivered via NAS signaling using similar behaviors as with SMS overNAS. During the registration phase, the WTRU and the network maynegotiate about how the small data over NAS is supported and realized.If the small data over NAS is enabled, the WTRU may send/receive smalldata in the NAS signaling to/from the AMF.

At any time, based on an operator's operations and maintenance (O&M) aswell as network configuration, a user's subscription may change. If thisoccurs, the home data base, Unified Data Management (UDM), may informand update the anchor node for mobility where the WTRU is registered. Ina 5G system (5GS), this anchor node may be the AMF. It should be notedthat the only way for a WTRU to be notified about any possible changemay be to perform a registration update procedure toward the AMF.

In 5GS, the AMF node may only be responsible for mobility managementsignaling. Service related signaling messages may either be exchangedbetween the WTRU and SMF (for establishing so called PDU Sessions),between the WTRU and SMSF (for the SMS over NAS traffic), or othernodes. The AMF may act as a relay when it comes to service relatedsignaling traffic by means of sending and receiving message to/from theWTRU and SMF/SMSF.

Two special NAS messages may be used (e.g., at the Mobility Managementlevel) between the WTRU and the AMF. These messages may be calleduplink/downlink (UL/DL) NAS Transport messages and may contain acontainer, which may be either a 5GSM message (for WTRU-SMFcommunication) or an SMS message (for WTRU-SMSF communication). Ineither direction, the AMF may extract the container and forward it tothe correct (SMF or SMSF) node. An information element (IE) may bedefined in the message that points out the type of container. This IEmay be called the Payload Container Type. The IE may also point outother nodes in the network.

The WTRU may be unaware of whether (or when) subscription changes on thenetwork side occur. The only way of having both the WTRU and the AMFsynchronized about the changes in subscription may be to have the WTRUgo through a registration update procedure. While the WTRU is normallysupposed to do a periodic registration (e.g., according to expiration ofa timer), it may take a very long time before it actually does that. Thetimer may be reset, both on the WTRU and on the NW side, each time theWTRU transitions from Idle to Connected Mode at the NAS level.

These issues may also exist in CIoT small data delivery (i.e., smalldata over NAS signaling). For example, the WTRU subscription on the CIoTfeature may also change to “not allowed” for small data over NAS. Inthis case, the WTRU may also be unaware of the subscription change onthe network side.

Considering the issues above, a mechanism may be needed for thenetwork/AMF to inform the WTRU about the changes in subscription.

Referring now to FIG. 6 , a diagram illustrating using a method ofupdating subscription type is shown. In step 1, when a WTRU 602 wants tosend an SMS or small data over NAS in Idle Mode, it may start thesignaling traffic by a Service Request procedure, hence transitioning tothe Connected Mode. The Service Request procedure may include sending aService Request message to the network. In step 2, an AMF 604 mayreceive a subscription change notification from a UDM or other NF forSMS or small data.

In step 3, the WTRU 602 may send a first portion of the SMS message orsmall data in an UL NAS Transport message. It may be possible that theSMS or small data is sent by the WTRU in the Service Request message.

In step 4, the AMF 604 may determine that the subscription for SMS orsmall data has changed, and therefore the AMF may not forward thecontainer to the SMSF (for SMS) or Network Exposure Function (NEF)/SMF(for small data).

In step 5, the AMF 604 may extract and discard the container containingthe SMS or small data.

In step 6, AMF 604 may send a DL NAS Transport message or DL NAS errormessage, including a dummy container (i.e., with no meaning) and acertain cause code. A new payload container type may be defined to pointout that this particular container is a dummy. In step 7, the cause codemay trigger a new behavior at the WTRU 602.

In step 8, the WTRU 602 to start a registration procedure. During theregistration procedure, the network (AMF 604) may inform the WTRU 602that the SMS over NAS or small data over NAS is not allowed anymore. TheWTRU may receive such indication in the registration accept message.

It should be noted that the AMF 604 may communicate the subscriptionchange to the WTRU 602 prior to the reception of a Service Requestprocedure from the WTRU 602 if the AMF 604 needs to contact the WTRU 602for other reasons (e.g., a UCU procedure triggered due, for instance toa Network Slice modification or deletion). This may prevent the WTRU 602from requesting SMS small data transmission. The AMF 604 may use theexisting registration/no registration indication to cause the WTRU 602to register.

The SMS or small data may be sent by the WTRU 602 in the Service Requestmessage when the WTRU 602 transitions to Connected Mode. The AMF 604 mayperform the procedure described above when it receives the ServiceRequest with small data or SMS container. Upon receiving the ServiceRequest, the AMF 604 may determine that the subscription for the SMS orsmall data has changed. The AMF 604 may discard the container in an ULNAS message and may create a response with the cause code to inform theWTRU 602 that the subscription for the service (SMS or small data haschanged. The AMF 604 may send the cause code in either the ServiceAccept or the Service Reject NAS message. Upon receiving the cause code,the WTRU 602 may be informed that SMS or SD is not supported due tosubscription change. The WTRU 602 may then perform a registrationprocedure triggered by this cause code.

Alternatively, the AMF 604 may forward the SMS or small data over NAS tothe SMSF or NEF/SMF. The AMF 604 may include the response from SMSF orNEF/SMF in the DL NAS Transport message and add the cause code, asdescribed above, to cause the WTRU 602 to perform registration update.

In another example, a WTRU Configuration Update (UCU) Command messagemay be used. In this example, the WTRU 602 may be in Connected Mode forreasons other than SMS traffic when the subscription change for SMS orsmall data over NAS occurs.

The AMF 604 may send a UCU Command message to the WTRU 602 on theexisting NAS signaling connection to inform the WTRU 602 that there is achange in subscription that requires a re-registration by the WTRU 602.The UCU Command message may include a specific cause code as describedabove.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising a processor and memory configured to: receive a first messagefrom a network via a first access technology, the first messagecomprising an indication for the WTRU to reestablish resources for aprotocol data unit (PDU) session, wherein the PDU session is associatedwith a second access technology and is locally de-activated at the WTRU;and send a second message via the first access technology, the secondmessage comprising a PDU session status information element (IE)indicating the PDU session is locally deactivated.
 2. The WTRU of claim1 further configured to: determine that the WTRU is in a limited servicestate associated with the second access technology.
 3. The WTRU of claim1 further configured to: register with the network via both the firstaccess technology and the second access technology.
 4. The WTRU of claim1 wherein the first access technology is a non-Third GenerationPartnership Project (non-3GPP) access technology and the second accesstechnology is a 3GPP access technology.
 5. The WTRU of claim 1 whereinthe first access technology is an IEEE 802.11 access technology and thesecond access technology is a 3GPP access technology.
 6. The WTRU ofclaim 1 wherein the WTRU is in connected mode (CM) in the first accesstechnology.
 7. The WTRU of claim 1 wherein the WTRU is in idle mode (IM)in the second access technology.
 8. The WTRU of claim 1 wherein thesecond message comprises a notification response message..
 9. The WTRUof claim 1 wherein the second message is a non-access stratum (NAS)message.
 10. A method for use in a wireless transmit/receive unit(WTRU), the method comprising: receiving a first message from a networkvia a first access technology, the first message comprising anindication for the WTRU to reestablish resources for one or moreprotocol data unit (PDU) sessions over a second access technology,wherein the second access technology is locally deactivated at the WTRU;and sending a second message via the first access technology, the secondmessage comprising a PDU session status information element (IE)indicating the PDU session is locally deactivated.
 11. The method ofclaim 10, further comprising: determining that the WTRU is in a limitedservice state associated with the second access technology.
 12. Themethod of claim 10, further comprising: registering with the networkover both the first access technology and the second access technology.13. The method of claim 10, wherein the first access technology is anon-Third Generation Partnership Project (non-3GPP) access technologyand the second access technology is a 3GPP access technology.
 14. Themethod of claim 10, wherein the first access technology is an IEEE802.11 access technology and the second access technology is a 3GPPaccess technology.
 15. The method of claim 10, wherein the networkcomprises an Access and Mobility Function (AMF) shared between the firstaccess technology and the second access technology.
 16. The method ofclaim 10, wherein the WTRU is in connected mode (CM) in the first accesstechnology.
 17. The method of claim 10, wherein the WTRU is in idle mode(IM) in the second access technology.
 18. The method of claim 10,wherein the second message is a non-access stratum (NAS) message. 19.The method of claim 10, wherein the second message comprises anotification response message.
 20. The method of claim 10, wherein thePDU session is locally deactivated while the WTRU is in a limitedservice state of the second access technology.